CN115650665B - High-heat-conductivity water-stopping backfill material and preparation method thereof - Google Patents
High-heat-conductivity water-stopping backfill material and preparation method thereof Download PDFInfo
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- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
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Abstract
The application relates to the technical field of backfill, and particularly discloses a high-heat-conductivity water-stopping backfill and a preparation method thereof. The high-heat-conductivity water-stopping backfill comprises the following components in parts by weight: 40-60 parts of modified expanded perlite; 30-60 parts of water; 20-40 parts of cement; 15-25 parts of yellow sand; 3-7 parts of an additive; the preparation method of the modified expanded perlite comprises the following steps: a-1, preparing a nano heat-conducting powder dispersion liquid, wherein the preparation raw materials comprise nano graphene, nano diamond and carbon nano tubes; a-2, pretreating the expanded perlite; and A-3, adding the pretreated expanded perlite into the nano heat-conducting powder dispersion liquid, dipping, drying and roasting to obtain the modified expanded perlite. The water-stopping backfill material with high heat conductivity has the advantages of high heat conductivity and good water-stopping effect.
Description
Technical Field
The application relates to the technical field of backfill, in particular to a high-heat-conductivity water-stopping backfill and a preparation method thereof.
Background
In the ground source heat pump engineering, the ground buried pipe heat exchange hole is filled with slurry for backfilling, backfilling is to fill backfilling material into the ground buried pipe heat exchange hole through grouting equipment, and the backfilling material plays roles of blocking water-bearing layer communication, exchanging heat with a rock-soil body and anchoring a heat exchange pipe after solidification.
At present, some enterprises also add expanded perlite into backfill, which has the effects of light weight, no toxicity, good filling effect and densely filling underground pores to reduce collapse; meanwhile, the holes on the expanded perlite are sealed through sintering, so that the water absorption rate is reduced, water is reduced from penetrating out of the holes, and the water stopping effect of the backfill is improved.
However, the expanded perlite is a high-efficiency heat-insulating material formed by calcining natural perlite, so that the heat-conducting property of the backfill is also reduced by adding the expanded perlite, thereby reducing the heat exchange effect of the heat exchanger. Therefore, there is an urgent need to provide a backfill material having good water-stopping property and good thermal conductivity.
Disclosure of Invention
In order to improve the heat conductivity of the backfill on the basis of guaranteeing low water absorption and good water stopping performance of the backfill, the application provides a high-heat-conductivity water stopping backfill and a preparation method thereof.
In a first aspect, the present application provides a water-stopping backfill material with high heat conductivity, which adopts the following technical scheme:
the high-heat-conductivity water-stopping backfill comprises the following components in parts by weight:
40-60 parts of modified expanded perlite;
30-60 parts of water;
20-40 parts of cement;
15-25 parts of yellow sand;
3-7 parts of an additive;
the preparation method of the modified expanded perlite comprises the following steps:
a-1, preparing a nano heat-conducting powder dispersion liquid, wherein the preparation raw materials comprise nano graphene, nano diamond and carbon nano tubes; a-2, pretreating the expanded perlite;
and A-3, adding the pretreated expanded perlite into the nano heat-conducting powder dispersion liquid, dipping, drying and roasting to obtain the modified expanded perlite.
By adopting the technical scheme, the performance test is carried out on the backfill prepared by the method, the water level drop height is 0.82m at most, the heat conductivity coefficient is above 2.89W/m.K, the compressive strength is above 1.56MPa, and all performances are superior to those of the backfill without using modified expanded perlite, so that the water absorption and permeability of the backfill are reduced, the backfill has good water stopping property and good heat conductivity;
the analysis may be that the nano heat-conducting powder is attached to the expanded perlite in the impregnation process, on one hand, the nano heat-conducting powder is filled in the pores on the expanded perlite, the pores are closed, the water absorption rate of the expanded perlite is reduced, the permeability of the expanded perlite is reduced, and the heat conductivity of the nano heat-conducting powder compounded by nano graphene, nano diamond and carbon nano tubes is improved; on the other hand, the nano heat-conducting powder is adhered to the surface of the expanded perlite to wrap the expanded perlite, so that the heat-conducting property of the expanded perlite is further improved; by reducing the permeability of the backfill and improving the heat conductivity coefficient, the water stopping property and the heat conductivity of the backfill are improved.
Optionally, in the step A-1, the weight ratio of the nano graphene to the nano diamond to the carbon nano tube is (4-5): 1 (8-12).
By adopting the technical scheme, the backfill prepared by the application is subjected to performance detection, and the heat conductivity coefficient of the backfill is 3.03-3.09W/m.K, so that the heat conductivity of the backfill is better when the weight ratio of the nano graphene, the nano diamond and the carbon nano tube is in the range.
Optionally, the modified expanded perlite is further subjected to coating treatment, and the coating liquid is formed by compounding redispersible emulsion powder, multi-wall carbon nanotubes, acrylic resin emulsion, EVA emulsion and cement paste with the water-cement ratio of 0.6-0.8.
Through adopting above-mentioned technical scheme, carry out performance test with the backfill that this application made, compare the backfill that does not use the modified expanded perlite of coating liquid cladding to make, the water level decline height of the backfill that uses the coating liquid further reduces, is 0.66m, compressive strength improves to 2.12MPa, from this indicates, when using the coating liquid cladding modified expanded perlite, further promotes the performance of backfill. The reason for this may be analyzed as follows:
1) The coating liquid coats the heat-conducting expanded perlite, so that the water absorption rate is further reduced;
2) The gel film formed after coating has good elasticity and toughness, is not easy to damage, gives certain elasticity and toughness to the heat-conducting expanded perlite, fully fills cement gaps, and improves the strength of the heat-conducting expanded perlite, thereby improving the compactness and structural strength of backfill; meanwhile, the formed gel film improves the roundness of the surface of the expanded perlite, so that the backfill has good fluidity and fully fills the pores.
3) The compatibility between the coating liquid and the cement is good, which is favorable for the dispersion of the heat-conducting expanded perlite in the backfill; meanwhile, the coating liquid coats the heat-conducting expanded perlite to form modified expanded perlite with a structure which is not easy to disperse, nano heat-conducting powder is not easy to separate from the surface of the expanded perlite, and the heat-conducting property of the backfill is ensured after the nano heat-conducting powder is mixed with water, cement and yellow sand.
Optionally, the coating liquid comprises the following components in percentage by weight:
2-4% of redispersible emulsion powder, 5-8% of multi-wall carbon nano tube, 30-40% of acrylic resin emulsion, 35-40% of EVA emulsion and the balance of cement paste.
By adopting the technical scheme, performance detection is carried out on the backfill prepared by the application, the heat conductivity coefficient of the backfill is improved to 3.11-3.15W/m.K, and compared with the heat conductivity of the non-used coating liquid which is 3.09W/m.K, the heat conductivity of the backfill is similar to or even slightly improved, so that when the use amount of each component in the coating liquid is in the range, the problem that the heat conductivity of the modified expanded perlite is reduced due to the coating layer coating can be balanced, and the prepared backfill has better heat conductivity and better water stopping property.
Optionally, the weight ratio of the addition amount of the coating liquid to the modified expanded perlite is (1.2-1.8): 1.
By adopting the technical scheme, the heat-conducting expanded perlite is coated by the coating liquid prepared from the components, the performance of the prepared modified expanded perlite on the backfill is improved remarkably, the performance of the backfill prepared by the method is detected, the water level is reduced to 0.55-0.58m, and the compressive strength is improved to 2.25-2.28MPa.
Optionally, in the step A-2, the pretreatment method of the expanded perlite comprises the following steps:
adding the expanded perlite into sulfuric acid with the concentration of 5-8mol/L, stirring and mixing, drying, activating at 90-110 ℃, washing, drying, crushing, and sieving with a 200-300 mesh sieve to obtain the product.
By adopting the technical scheme, the acid modification is carried out on the expanded perlite by sulfuric acid, the surface characteristics of the expanded perlite are changed, the porosity of the expanded perlite is increased, the loading capacity of the expanded perlite on the nano heat-conducting powder is improved, and the heat-conducting property of the backfill is further improved.
Optionally, in the step A-3, the weight ratio of the expanded perlite to the nano heat-conducting powder dispersion liquid is 1 (3-6).
Optionally, the weight ratio of water to cement to modified expanded perlite to yellow sand is (4-5) 3 (4.5-5.5) 1.8-2.2.
By adopting the technical scheme, the water stopping performance, the heat conducting performance and the compressive strength of the backfill are further improved by controlling the weight ratio of the expanded perlite to the nano heat conducting powder dispersion liquid and the weight ratio of cement to the modified expanded perlite to yellow sand.
Optionally, the yellow sand is a mixture of fine sand with fineness of 1.6-2.2 mu F, middle sand with fineness of 2.3-3.2 mu F and coarse sand with fineness of 3.1-3.7 mu F according to the weight ratio of (5-6): 3-4): 1.
By adopting the technical scheme, the fluidity of the backfill is improved, the pores are densely filled, and the water stopping property of the backfill is improved by using yellow sand with relatively high fineness; the backfill prepared by the method is subjected to performance detection, the water level reduction height is only 0.48-0.50m, and the water stopping performance of the backfill is better.
In a second aspect, the present application provides a method for preparing a water-stopping backfill with high heat conductivity, which adopts the following technical scheme:
a preparation method of a water-stopping backfill with high heat conductivity comprises the following steps:
b-1, adding cement into water, and stirring and mixing to obtain a mixed solution A;
b-2, adding the modified expanded perlite and the additive into the mixed solution A, and stirring and mixing to obtain a mixed solution B;
and B-3, adding yellow sand into the mixed solution B, and stirring and mixing to obtain the backfill.
By adopting the technical scheme, the process is simple, the efficiency is higher, and the prepared backfill material has good heat conduction performance, good water stopping performance and high compressive strength.
In summary, the present application has the following beneficial effects:
1. according to the method, the expanded perlite is impregnated by the nano heat-conducting powder dispersion liquid, so that on one hand, the nano heat-conducting powder fills the pores of the expanded perlite, the permeability of the expanded perlite is reduced, and on the other hand, the heat conductivity of the expanded perlite is improved, and therefore, the backfill prepared by using the modified expanded perlite has good water stopping performance and heat conductivity;
2. in the method, the coating liquid is used for impregnating the modified expanded perlite, so that a layer of coating layer is formed on the surface of the modified expanded perlite, the permeability of the modified expanded perlite is further reduced, and the coating layer has better heat conductivity through the selection of components of the coating liquid and the adjustment of the proportion;
3. the method has simple process, can be suitable for industrial mass production, and can prepare the backfill with good water stopping property and good thermal conductivity.
Detailed Description
The present application is described in further detail below with reference to examples.
Preparation example
Preparation example 1
The modified expanded perlite is prepared by the following steps:
a-1, preparing a nano heat-conducting powder dispersion liquid: adding 4kg of nano graphene, 1.2kg of nano diamond, 8kg of carbon nano tube, 1.5kg of triethanolamine and 1kg of dispersant NNO into every 100kg of water, and performing ultrasonic dispersion under the following ultrasonic conditions: the temperature is 40 ℃, the time is 30min, and the power is 150W;
wherein, the nanometer graphene is manufactured by Jiangsu Qingjiu new material Co., ltd, the grain diameter is 0.012mm, and the nanometer graphene is in powder form;
nano diamond, the manufacturer is Guangzhou Hongwu materials science and technology Co., ltd, product number C960, particle size is 10nm, powder;
the manufacturer of the carbon nano tube is new material limited company of Jiaxing Nake, the product number is NACO-CNTs-1, the fineness is 7-15nm, and the carbon nano tube is in powder form; and A-2, pretreating the expanded perlite: adding the expanded perlite into sulfuric acid with the concentration of 4mol/L according to the weight ratio of 1:2, stirring and mixing for 2 hours at 60 ℃, drying to constant weight at 40 ℃, and activating for 1 hour at 80 ℃; spraying deionized water with the weight 1.5 times of that of the expanded perlite, washing, crushing and sieving with a 200-mesh sieve;
wherein, expanded perlite: the manufacturer is Shijia Ruichang agricultural technology Co., ltd, trade mark 2021-7;
and A-3, adding 10kg of pretreated expanded perlite into 25kg of nano heat-conducting powder dispersion liquid, soaking for 5h, drying at 50 ℃ to constant weight, roasting at 200 ℃ for 20min for the first time, roasting at 300 ℃ for 10min for the second time, roasting at 400 ℃ for 10min for the third time, and cooling to obtain the modified expanded perlite.
Preparation example 2
The difference between the modified expanded perlite and the preparation example 1 is that in the step A-1, the total weight of the nano graphene, the nano diamond and the carbon nano tube is unchanged, but the weight ratio is different, specifically, the weight ratio of the nano graphene, the nano diamond and the carbon nano tube is 4:1:8.
Preparation example 3
The difference between the modified expanded perlite and the preparation example 1 is that in the step A-1, the total weight of the nano graphene, the nano diamond and the carbon nano tube is unchanged, but the weight ratio is different, specifically, the weight ratio of the nano graphene, the nano diamond and the carbon nano tube is 4.5:1:10.
Preparation example 4
The difference between the modified expanded perlite and the preparation example 1 is that in the step A-1, the total weight of the nano graphene, the nano diamond and the carbon nano tube is unchanged, but the weight ratio is different, specifically, the weight ratio of the nano graphene, the nano diamond and the carbon nano tube is 5:1:12.
Preparation example 5
The modified expanded perlite is different from the preparation example 3 in that the expanded perlite is subjected to coating treatment after being immersed and dried: spraying the coating liquid on the surface of the dried expanded perlite according to the weight ratio of 1:1, standing for 24 hours, and drying at 50 ℃ until the weight is constant, thus obtaining the modified perlite;
wherein, the coating liquid is prepared by mixing and compounding the components according to the usage amount of each component of 100kg shown in the table 1.
Preparation examples 6 to 11
The difference between the modified expanded perlite and the preparation example 5 is that the amounts of the components used in the coating liquid are different, and the amounts of the components used per 100kg are shown in Table 1.
TABLE 1 Each of the components of preparation examples 5-11 and weight (kg)
Redispersible emulsion powder: redispersible latex powder VAE;
multiwall carbon nanotubes: the manufacturer is Guangzhou Hongwu materials science and technology Co., ltd, the diameter is 100nm, and the length is 1-2 μm;
acrylic resin emulsion: manufacturer Jining Malus asiatica chemical industry Co., ltd., product number E0544;
EVA emulsion: the manufacturer is Guangzhou City Guanghua chemical industry Co., ltd, and the product number is DA-102;
cement paste: the water-cement ratio is 1:0.7, and is obtained by mixing ordinary Portland cement (PO 42.5) with water.
Preparation example 12
The difference between the modified expanded perlite and the preparation example 7 is that the weight ratio of the addition amount of the coating liquid to the heat-conducting expanded perlite is 1.2:1.
Preparation example 13
The difference between the modified expanded perlite and the preparation example 7 is that the weight ratio of the addition amount of the coating liquid to the heat-conducting expanded perlite is 1.5:1.
PREPARATION EXAMPLE 14
The difference between the modified expanded perlite and the preparation example 7 is that the weight ratio of the addition amount of the coating liquid to the heat-conducting expanded perlite is 1.8:1.
Preparation example 15
The modified expanded perlite is different from preparation example 13 in that in the step A-2, the pretreatment method of the expanded perlite is different, specifically, the concentration of sulfuric acid is 6mol/L, and the activation temperature is 90 ℃.
PREPARATION EXAMPLE 16
The modified expanded perlite is different from preparation example 13 in that in the step A-2, the pretreatment method of the expanded perlite is different, specifically, the concentration of sulfuric acid is 7mol/L, and the activation temperature is 100 ℃.
Preparation example 17
The modified expanded perlite is different from preparation example 13 in that in the step A-2, the pretreatment method of the expanded perlite is different, specifically, the concentration of sulfuric acid is 8mol/L, and the activation temperature is 110 ℃.
PREPARATION EXAMPLE 18
The modified expanded perlite is different from the preparation example 16 in that in the step A-3, the dispersion liquid of the nano heat-conducting powder is used in different amounts, specifically;
the weight ratio of the expanded perlite to the nano heat-conducting powder dispersion liquid is 1:3.
Preparation example 19
The modified expanded perlite is different from the preparation example 16 in that in the step A-3, the dispersion liquid of the nano heat-conducting powder is used in different amounts, specifically;
the weight ratio of the expanded perlite to the nano heat-conducting powder dispersion liquid is 1:5.
Preparation example 20
The modified expanded perlite is different from the preparation example 16 in that in the step A-3, the dispersion liquid of the nano heat-conducting powder is used in different amounts, specifically;
the weight ratio of the expanded perlite to the nano heat-conducting powder dispersion liquid is 1:6.
Examples
Example 1
The water-stopping backfill with high heat conductivity is prepared by the following components and the corresponding weights shown in table 2: adding cement into water, stirring and mixing at 25 ℃ for 5min to obtain a mixed solution A;
b-2, adding the modified expanded perlite and the additive into the mixed solution A, stirring and mixing at 25 ℃ for 3min to obtain a mixed solution B;
adding yellow sand into the mixed solution B, stirring and mixing at 25 ℃ for 3min to obtain backfill;
wherein, the modified expanded perlite is prepared by a preparation example 1;
the cement is ordinary Portland cement (PO 42.5);
the additive is S95 grade mineral powder specified in the national standard GB/T18046-2000;
yellow sand is a mixture of middle sand with fineness of 2.3-3.2 mu F and coarse sand with fineness of 3.1-3.7 mu F according to a weight ratio of 7:3.
Comparative example 1
Backfill differs from example 1 in that an equal amount of expanded perlite is used instead of modified expanded perlite.
Comparative example 2
The backfill differs from example 1 in that the nano-powder dispersion was prepared from a starting material that did not contain nanodiamond, and that an equivalent amount of nanographene was used instead of nanodiamond.
Comparative example 3
The backfill differs from example 1 in that the raw materials for preparing the nano powder dispersion do not contain carbon nanotubes, and the nano graphene is used in the same amount instead of carbon nanotubes.
Comparative example 4
The backfill differs from example 1 in that the expanded perlite is not pre-treated during the preparation of the backfill.
Examples 2 to 5
The difference between the water-stopping backfill with high heat conductivity and the embodiment 1 is that the usage amount of each component is different, and the specific usage amount is shown in table 2.
Comparative examples 5 to 6
The backfill differs from example 1 in the amounts of the components used, as shown in Table 2.
Table 2 Components in examples 1 to 5 and comparative examples 5 to 6 and weights (kg)
Examples 6 to 8
The difference between the high thermal conductivity water-stopping backfill and the example 3 is that the modified expanded perlite is used in different conditions, as shown in Table 3.
Example 9
The difference between the high thermal conductivity water-stopping backfill and example 7 is that the modified expanded perlite is used differently, as shown in Table 3.
Examples 10 to 15
The difference between the high thermal conductivity water-stopping backfill and example 9 is that the modified expanded perlite is used differently, as shown in Table 3.
Examples 16 to 18
A water-stopping backfill with high heat conductivity differs from example 11 in the use of the modified expanded perlite, as shown in Table 3.
Examples 19 to 21
A water-stopping backfill with high heat conductivity differs from example 17 in the use of the modified expanded perlite, as shown in Table 3.
Examples 22 to 24
A water-stopping backfill with high thermal conductivity differs from example 20 in the use of the modified expanded perlite, as shown in Table 3.
TABLE 3 usage of modified expanded perlite in examples 6-24
Example 25
A water-stopping backfill with high heat conductivity is different from the embodiment 23 in that yellow sand is a mixture of fine sand with fineness of 1.6-2.2 mu F, middle sand with fineness of 2.3-3.2 mu F and coarse sand with fineness of 3.1-3.7 mu F according to a weight ratio of 5:3:1.
Example 26
A water-stopping backfill with high heat conductivity is different from the embodiment 23 in that yellow sand is a mixture of fine sand with fineness of 1.6-2.2 mu F, middle sand with fineness of 2.3-3.2 mu F and coarse sand with fineness of 3.1-3.7 mu F according to a weight ratio of 5.5:3.5:1.
Example 27
A water-stopping backfill with high heat conductivity is different from the embodiment 23 in that yellow sand is a mixture of fine sand with fineness of 1.6-2.2 mu F, middle sand with fineness of 2.3-3.2 mu F and coarse sand with fineness of 3.1-3.7 mu F according to a weight ratio of 6:4:1.
Performance detection
Detection method
The backfill materials prepared in the examples and comparative examples were selected and tested as follows, and the test results are recorded in table 4.
Test one: and (3) detecting heat conduction performance: the backfill (24 hours) was tested for thermal conductivity in W/mK using a Hot Disk TPS2500S thermal constant analyzer.
And (2) testing II: and (3) water stopping performance detection: constructing according to hydrologic wells on site, wherein 2 hydrologic wells with numbers J1 and J2 are adopted, and each hydrologic well is reamed by 5; the backfill prepared in the comparative example is backfilled in the J1 hole, the backfill prepared in the backfill example in the J2 hole is filled in the well, the water level in the 2-mouth water Wen Jing is respectively recorded to drop the height per unit m after 12 hours, the smaller the drop height is, the better the water stopping effect of the backfill is indicated, and the compactness is higher.
And (3) test III: and (3) detecting the compressive strength, namely detecting the compressive strength of the backfill after natural curing for 7 days according to GB/T17671-2020 cement mortar strength test method (ISO method) in MPa.
TABLE 4 Performance test results
The following analysis was performed on a water-stopping backfill material with good thermal conductivity prepared in this application, in combination with the corresponding data in examples 1-27, comparative examples 1-6 and Table 4.
In example 1, the performance of the backfill material obtained by using the modified expanded perlite obtained in preparation example 1 is that the water level drop height is only 0.82m, the heat conductivity coefficient is as high as 2.89W/m.K, and the compressive strength is as high as 1.56MPa; in contrast, in comparative example 1, the performance of the backfill material obtained by using the unmodified expanded perlite is that the water level is reduced by 1.48m, the heat conductivity coefficient is only 1.23W/m.K, and the compressive strength is only 0.55MPa; the backfill of example 1 has significantly better properties than comparative example 1;
therefore, the prepared backfill material has good water stopping property, good thermal conductivity and high compressive strength by using the modified expanded perlite.
The reason for analysis is probably that by using the nano heat-conducting powder to fill the pores of the expanded perlite and attach the pores on the surface of the expanded perlite, the water absorption and permeability of the expanded perlite are reduced, and the heat conductivity is improved, so that the backfill with good heat conductivity and good water stopping property is prepared after the nano heat-conducting powder is fully mixed with cement and yellow sand.
Comparative examples 2 and 3 each had a different degree of deterioration in the properties of the backfill material of comparative examples 2 and 3 compared to example 1 due to the lack of a portion of the components during the preparation of the modified expanded perlite. The reason why the data in comparative example 2 is inferior to that in comparative example 3 may be that nanodiamond is included in both the preparation raw material in comparative example 3 and in the examples, and the nanodiamond has an abrasion effect, resulting in a large number of uniform and minute cracks on the surface of the expanded perlite, improving the impregnation effect of the dispersion of the nano heat conductive powder, and thus the heat conductivity in comparative example 3 is higher than that in comparative example 2, but has little influence on the water level lowering height and the compressive strength.
Comparative example 4 because the expanded perlite was not pretreated during the preparation of the modified expanded perlite, the heat conductive properties of the backfill material in comparative example 4 were somewhat reduced, but the compressive strength was slightly improved, as compared to example 1, and the analysis was probably due to the fact that the strength of the expanded perlite was slightly reduced, but not significantly affected, after the expanded perlite was corroded with the acid solution in examples 1 to 5.
Examples 1 to 5 and comparative examples 5 to 6 differ in the amounts of the components used for the backfill. The performances in the embodiments 1-5 are good, the water level drop height is only 0.75-0.82m, the heat conductivity coefficient is up to 2.89-2.95W/m.K, and the compressive strength is up to 1.56-1.64MPa; each performance of comparative examples 5 to 6 is inferior to examples 1 to 5, and the water level drop height is only 0.95 to 1.01m, the heat conductivity coefficient is 2.56 to 2.60W/mK, and the compressive strength is 1.12 to 1.18MPa; it is thus shown that the various properties of the backfill are better when the amounts of the components used are in the range of examples 1-5, in particular examples 2-4.
Examples 6 to 8 are different from example 3 in that the weight ratio of the nano graphene, the nano diamond and the carbon nano tube is different in the preparation process of the modified expanded perlite, each performance of examples 6 to 8 is improved, the water level is reduced by only 0.71 to 0.74m, the heat conductivity coefficient is 3.03 to 3.09W/m.K, and the compressive strength is 1.67 to 1.75MPa, so that the heat conductivity of the backfill is better, the water stopping performance is better, and the compressive strength is higher when the use amount of the nano graphene, the nano diamond and the carbon nano tube is in the range of examples 6 to 8.
In the embodiment 8, the compression resistance of the backfill is better due to the higher carbon nanotube ratio, but the heat conduction performance and the water level drop height are both inferior to those of the embodiment 7, and the embodiment 7 is a preferred embodiment by integrating various data.
Example 9 differs from example 7 in that in the preparation process of the modified expanded perlite, after the expanded impregnation liquid is impregnated and dried, the coating treatment is further carried out, and the coating liquid forms a layer of elastic and tough film which is not easy to damage on the surface of the expanded perlite, so that the permeability of the expanded perlite is reduced, the water level of the prepared backfill is reduced by only 0.66m, the compressive strength is as high as 2.12MPa, but the heat conduction performance is slightly reduced, and the reason is probably that the existence of the film reduces the heat conduction of the modified expanded perlite to a certain extent.
Examples 10-15 differ from example 9 in that the coating solution was different in weight percentages of each component during the preparation of the modified expanded perlite. The data of examples 10-12 show that the polyacrylic resin emulsion, EVA emulsion, cement paste, dispersible emulsion powder and multi-wall carbon nano tube have certain compounding effect, and all performances of the prepared backfill are improved; from the data of examples 9 and 11, it is known that the heat conducting property of the backfill can be improved by increasing the ratio of the multiwall carbon nanotubes within a certain range, and the influence of the film on the reduction of the heat conducting property of the backfill can be balanced.
As can be seen from the data of examples 9, 11 and 13, the performances of example 13 are slightly reduced, which indicates that the higher the ratio of the non-multiwall carbon nanotubes is, the better the heat conduction effect is; the greater water level drop compared to examples 11 and 14 indicates a reduced EVA emulsion duty cycle and reduced backfill water stopping performance; in example 15, the compressive strength and thermal conductivity were slightly reduced compared to example 11, indicating that the ratio of cement paste was reduced and the compressive strength of backfill was reduced, which was analyzed for the possible reason that the strength of the modified expanded perlite was increased by using cement paste on the one hand and the compatibility between the modified expanded perlite and cement on the other hand.
Examples 16-18 differ from example 11 in the amount of coating added during the preparation of the modified expanded perlite. In examples 16-18, the height of the water level drop was reduced to 0.55-0.58m, and the compressive strength was increased to 2.25-2.28MPa, indicating that when the addition amount of the coating liquid was in the range of examples 16-18, the heat conductive property was further improved, but the heat conductive property was slightly reduced, and the analysis was that the reason was probably that the coating liquid formed a film on the surface of the expanded perlite that was too thick, although the heat conductive property of the formed film was good, the heat conductive property of the backfill was slightly reduced with the increase of the thickness.
Examples 19-21 differ from example 17 in that the pretreatment process was different, and each of the properties of the backfill materials in examples 19-21 was further improved, indicating that the performance of the backfill materials was better when the pretreatment conditions were the conditions of examples 19-21.
Examples 22-24 differ from example 20 in that the amount of the nano heat conductive powder dispersion used was varied, and the heat conductivity of the backfill material in examples 22-24 was increased to 3.21-3.25W/mK, indicating that the heat conductive properties of the backfill material were better when the weight ratio of nano powder dispersion to expanded perlite was in the range of examples 22-24.
Examples 25 to 27 are different from example 23 in that yellow sand is used in different conditions, the heat conduction performance of the backfill material in examples 25 to 27 is slightly improved, but the change is small, the water level drop height is obviously reduced to 0.48 to 0.50m, and the water stopping performance of the backfill material is better.
The present embodiment is merely illustrative of the present application and is not intended to be limiting, and those skilled in the art, after having read the present specification, may make modifications to the present embodiment without creative contribution as required, but is protected by patent laws within the scope of the claims of the present application.
Claims (9)
1. The high-heat-conductivity water-stopping backfill is characterized by comprising the following components in parts by weight:
40-60 parts of modified expanded perlite;
30-60 parts of water;
20-40 parts of cement;
15-25 parts of yellow sand;
3-7 parts of mineral powder;
the preparation method of the modified expanded perlite comprises the following steps:
a-1, preparing a nano heat-conducting powder dispersion liquid, wherein the preparation raw materials comprise nano graphene, nano diamond and carbon nano tubes;
a-2, pretreating the expanded perlite;
adding the pretreated expanded perlite into the nano heat-conducting powder dispersion liquid, soaking, drying and roasting to obtain modified expanded perlite;
the modified expanded perlite is further impregnated with a coating liquid, wherein the coating liquid is formed by compounding redispersible latex powder, multi-wall carbon nanotubes, acrylic resin emulsion, EVA emulsion and cement paste with the water-cement ratio of 0.6-0.8.
2. The high thermal conductivity water stopping backfill of claim 1, wherein: in the step A-1, the weight ratio of the nano graphene to the nano diamond to the carbon nano tube is (4-5): 1 (8-12).
3. The high thermal conductivity water stopping backfill of claim 1, wherein: the coating liquid comprises the following components in percentage by weight:
2-4% of redispersible emulsion powder, 5-8% of multi-wall carbon nano tube, 30-40% of acrylic resin emulsion, 35-40% of EVA emulsion and the balance of cement paste.
4. A highly thermally conductive water-stopping backfill as set forth in claim 3 wherein: the weight ratio of the addition amount of the coating liquid to the modified expanded perlite is (1.2-1.8): 1.
5. The high thermal conductivity water stopping backfill of claim 1, wherein: in the step A-2, the pretreatment method of the expanded perlite comprises the following steps:
adding the expanded perlite into sulfuric acid with the concentration of 5-8mol/L, stirring and mixing, drying, activating at 90-110 ℃, washing, drying, crushing, and sieving with a 200-300 mesh sieve to obtain the product.
6. The high thermal conductivity water stopping backfill of claim 1, wherein: in the step A-3, the weight ratio of the expanded perlite to the nano heat-conducting powder dispersion liquid is 1 (3-6).
7. The high thermal conductivity water stopping backfill of claim 1, wherein: the weight ratio of water, cement, modified expanded perlite and yellow sand is (4-5) 3 (4.5-5.5) 1.8-2.2.
8. The high thermal conductivity water stopping backfill of claim 1, wherein: the yellow sand is a mixture of fine sand with fineness of 1.6-2.2 mu F, middle sand with fineness of 2.3-3.2 mu F and coarse sand with fineness of 3.1-3.7 mu F according to the weight ratio of (5-6): 3-4): 1.
9. A method of preparing the high thermal conductivity water stopping backfill material of any one of claims 1-8, comprising the steps of:
b-1, adding cement into water, and stirring and mixing to obtain a mixed solution A;
b-2, adding the modified expanded perlite and the mineral powder into the mixed solution A, and stirring and mixing to obtain a mixed solution B;
and B-3, adding yellow sand into the mixed solution B, and stirring and mixing to obtain the backfill.
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Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| WO1990014319A1 (en) * | 1989-05-22 | 1990-11-29 | Advanced Concrete Technology, Inc. | High strength structural perlite concrete |
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| US8299159B2 (en) * | 2009-08-17 | 2012-10-30 | Laird Technologies, Inc. | Highly thermally-conductive moldable thermoplastic composites and compositions |
| CN104610815A (en) * | 2015-02-02 | 2015-05-13 | 芜湖市宝艺游乐科技设备有限公司 | High-wearability polyethylene powder coating containing nano-diamond grafted activated expanded perlite and preparation method of powder |
| CN106893070A (en) * | 2015-12-17 | 2017-06-27 | 辽宁法库陶瓷工程技术研究中心 | A kind of surface-closed perlite filled polyurethane compound insulating material and preparation method |
| CN108328602B (en) * | 2018-01-23 | 2020-10-23 | 吴珊珊 | Carbon nano tube nano particle composite thermal insulation material and preparation method thereof |
| CN111607261B (en) * | 2020-07-04 | 2021-12-28 | 富华防水科技股份有限公司 | Efficient and rapid leaking stoppage waterproof coating and preparation method thereof |
| CN112960950B (en) * | 2021-03-01 | 2022-07-12 | 河南省一地建筑科学研究院有限公司 | Ground type heating light backfill material and construction method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO1990014319A1 (en) * | 1989-05-22 | 1990-11-29 | Advanced Concrete Technology, Inc. | High strength structural perlite concrete |
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